Method and apparatus for transferring a semiconductor substrate

ABSTRACT

A method and apparatus for transferring a substrate is provided. In one embodiment, an apparatus for transferring a substrate includes at least one end effector. A disk is rotatably coupled to the end effector. The disk is adapted to rotate the substrate relative to the end effector. The end effector may additionally include a sensor coupled thereto. The sensor is adapted to detect an indicia of orientation of the substrate supported by the end effector. In another embodiment, a method for transferring a substrate includes rotating the substrate disposed on an end effector and detecting an indicia of orientation of the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.09/882,394, filed Jun. 13, 2001, now U.S. Pat. No. 6,752,585, which isherein incorporated by reference in its entirety.

BACKGROUND OF THE DISCLOSURE

1. Field of the Invention

The embodiments of the present invention generally relate to a methodand apparatus for transferring a semiconductor substrate.

2. Background of Invention

Semiconductor substrate processing is typically performed by subjectinga substrate to a plurality of sequential processes to create devices,conductors and insulators on the substrate. These processes aregenerally performed in a processing chamber configured to perform asingle step of the production process. In order to efficiently completethe entire sequence of processing steps, a number of processing chambersare typically coupled to a central transfer chamber that houses a robotto facilitate transfer of the substrate between the processing chambers.A semiconductor processing platform having this configuration isgenerally known as a cluster tool, examples of which are the family ofCENTURA® and ENDURA® processing platforms available from AppliedMaterials, Inc. of Santa Clara, Calif.

Generally, a cluster tool consists of a central transfer chamber havinga robot disposed therein. The transfer chamber is typically surroundedby one or more processing chambers, at least one load lock chamber andsometimes a dedicated orientation chamber. The processing chambers aregenerally utilized to process the substrate, for example, performingvarious processing steps such as etching, physical vapor deposition,chemical vapor deposition, ion implantation, lithography and the like.Processed and unprocessed substrates are housed in a substrate storagecassette disposed in a factory interface coupled to the load lockchamber. The load lock chamber is isolated from the factory interfaceand the transfer chamber by slit valves. Substrates enter the transferchamber from the substrate storage cassettes one at a time through theload lock. The substrate is first positioned in the load lock after thesubstrate is removed from the cassette. The load lock is then sealed andpumped down to match the operating environment of the substrate transferchamber. The slit valve between the load lock and transfer chamber isthen opened, allowing the substrate transfer robot to access thesubstrates disposed in the substrate storage cassette. In this fashion,substrates may be transferred into and out of the transfer chamberwithout having to repeatedly re-establish transfer chamber vacuum levelsafter each substrate passes through the load lock.

Some processes such as etching and ion implantation require that thesubstrate have a particular orientation. Typically, substrates includean indicia, such as a notch or a flat on their perimeters in apre-defined location, that is typically indicative of the orientation ofthe substrate. This notch is used as a reference point when orientationof the substrate is required.

Typically, orientation of the substrate occurs in the orientationchamber. The orientation chamber generally includes a platform forrotating the substrate and a sensor for detecting the notch or flat onthe substrate's perimeter. For example, the platform disposed in theorientator supports the substrate. A shaft is coupled between theplatform and a stepper or servo motor to controllably rotate thesubstrate. A light source is positioned in the orientator near the edgeof the substrate and is directed across the substrate's edge to asensor. The light source is normally blocked by the substrate'sperimeter as the perimeter rotates. As the indicia (e.g., the notch orflat) rotates to a position between the light source and sensor, thelight beam passes therethrough and impinges on the sensor. The sensor,in response to the impingement of the light beam, indicates the positionof the notch, which accordingly, is indicative of the angularorientation of the substrate. Once the position of the notch isdetermined, the motor is able to rotate the platform and places thenotch in a pre-determined angular position that can be referencedthroughout the cluster tool and associated chambers.

Although the use of a dedicated orientation chamber coupled to thecluster tool has traditionally provided a robust process for determiningthe orientation of a substrate, the demand in the semiconductor industryfor reduced cost of tool ownership and increased substrate throughputhas made the use of a dedicated orientation chamber undesirable. Forexample, a dedicated orientation chamber increases the cluster toolhardware and software cost. Moreover, the orientation chamber mayutilize a position on the cluster tool that could be allocated to anadditional process chamber. Additionally, the use of a dedicatedorientation chamber requires a time expenditure that is not directlyrelated to processing. For example, time is spent transferring thesubstrate into the orientation chamber, clearing the robot arm from theorientation chamber, spinning (i.e., orientating) the substrate andretrieving the substrate. This time is significant as the orientationprocess takes about six to fourteen seconds to execute.

Therefore, there is a need for an improved method and apparatus fortransferring a substrate.

SUMMARY OF INVENTION

One aspect of the present invention generally provides an apparatus fortransferring a substrate. In one embodiment, an apparatus fortransferring a substrate is provided that includes at least one endeffector. A disk is rotatably coupled to the end effector. The disk isadapted to support the substrate while rotating the substrate relativeto the end effector.

In another embodiment, an apparatus for transferring a substrateincludes an end effector that has a sensor coupled thereto. The sensoris adapted to detect an indicia of orientation of the substratesupported by the end effector.

In another embodiment, an apparatus for transferring a substrateincludes a chamber that has a robot disposed therein. An end effectorhaving a disk rotatably disposed thereon is coupled to the robot. Atleast one sensor is disposed on the end effector and is adapted todetect an indicia of orientation of the substrate as the substrate isrotated on the disk.

In another aspect, a method for transferring a substrate is provided. Inone embodiment, a method for transferring a substrate includes rotatingthe substrate disposed on an end effector and detecting an indicia oforientation of the substrate.

In another embodiment, a method for transferring a substrate includessupporting the substrate on an end effector of a robot and rotating tosubstrate relative to the end effector.

BRIEF DESCRIPTION OF DRAWINGS

The teachings of the present invention can readily be understood byconsidering the following detailed description in conjunction with theaccompanying drawings in which:

FIG. 1 depicts an exemplary processing system having one embodiment of asubstrate transfer mechanism;

FIG. 2 depicts an elevation of the substrate transfer mechanism of FIG.1;

FIG. 3 depicts a plan view of one embodiment of an end effector;

FIG. 4 depicts a plan view of the end effector of FIG. 3 illustrating amotor assembly;

FIG. 5 depicts a sectional view of the end effector of FIG. 3;

FIG. 6 depicts a sectional view of another embodiment of an endeffector; and

FIG. 7 depicts another embodiment of a substrate transfer mechanism.

To facilitate understanding, identical reference numerals have beenused, wherever possible, to designate identical elements that are commonto the figures.

DETAILED DESCRIPTION OF INVENTION

FIG. 1 depicts a processing system 100 having one embodiment of asubstrate transfer mechanism 120 of the present invention disposedtherein. The exemplary processing system 100 additionally includes afactory interface 102, a transfer chamber 104, a least one load lockchamber 106 and a plurality of process chambers 108. One example of aprocessing system that may be adapted to benefit from the invention isan ENDURA® processing platform, available from Applied Materials, Inc.,of Santa Clara, Calif. Although the substrate transfer mechanism 120 isdescribed disposed in the exemplary processing system 100, thedescription is one of illustration and, accordingly, the substratetransfer mechanism 120 has utility wherever substrate orientation isdesired.

The transfer chamber 104 is generally fabricated from a single piece ofmaterial such as aluminum. The chamber 104 defines an evacuable interior122 through which substrates 124 are transferred between the processchambers 108 coupled to the exterior of the chamber 104. A pumpingsystem (not shown) is coupled to the chamber 104 through a pumping port114 disposed on the chamber's floor to maintain vacuum within thechamber 104. In one embodiment, the pumping system includes a roughingpump coupled in tandem to a turbomolecular or cryogenic pump.

The process chambers 108 are typically bolted to the exterior of thetransfer chamber 104. Examples of process chambers 108 that may beutilized are etching chambers, physical vapor deposition chambers,chemical vapor deposition chambers, ion implantation chambers,lithography chambers and the like. Different process chambers 108 may becoupled to the transfer chamber 104 to provide a processing sequencenecessary to form a predefined structure or feature upon the substrate'ssurface. A slit valve 116 is disposed between each process chamber 108and the transfer chamber 104 to maintain isolation between theenvironments of the chambers 108, 104 except during transfer of thesubstrate 124 therebetween.

The load lock chambers 106 (two are shown) are generally coupled betweenthe factory interface 102 and the transfer chamber 104. The load lockchambers 106 are generally used to facilitate transfer of the substrates124 between the vacuum environment of the interior 122 of the transferchamber 104 and the environment of the factory interface 102 which istypically held at or near atmospheric pressure. Each load lock chamber106 is isolated from the interior 122 of the transfer chamber 104 by oneof the slit valves 116. Each load lock chamber 106 additionally includesa door 126 disposed between the chamber 106 and the factory interface102. The door 126 may be opened to allow the substrate transfermechanism 120 transfer the substrate 124 into the load lock chamber 106.After the substrate transfer mechanism 120 is removed from the load lockchamber 106, the door 126 is closed to isolate the load lock 106. Oncethe atmosphere within the load lock 106 is substantially equal to thatof the transfer chamber 104, the slit valve 116 is opened and thesubstrate 124 is retrieved into the interior 122 of the transfer chamber104. Transfer of the substrate 124 from the transfer chamber 104 to theload lock 106 is performed similarly in the reverse order.

A first transfer robot 112A and a second transfer robot 112B aredisposed in the interior 122 of the transfer chamber 104 to facilitatetransfer of substrates between the process chambers 108. The robots112A, 112B may be of the dual or single blade variety. The robots 112A,112B typically have a “frog-leg” linkage that is commonly used totransfer substrates in vacuum environments. The first robot 112A isgenerally disposed in an end of the transfer chamber 104 adjacent theload locks 106. The second robot 112B is disposed in an opposite end ofthe transfer chamber 104 such that each robot 112A, 112B services theadjacent process chambers 108. One or more transfer platforms 118 aregenerally provided in the interior 122 of the chamber 104 to facilitatesubstrate transfer between robots 112A, 112B. For example, a substrateretrieved from one of the load locks 106 by the first robot 112A is setdown on one of the platforms 118. After the first robot 112A is clearedfrom the platform 118 supporting the substrate 124, the second robot112B retrieves the substrate from the platform 118. The second robot112B may then transfer the substrate to one of the process chambers 108serviced by the second robot 108 at that end of the transfer chamber104.

To facilitate process control of the system 100, a controller (notshown) comprising a central processing unit (CPU), support circuits andmemory, is coupled to the system 100. The CPU may be one of any form ofcomputer processor that can be used in an industrial setting forcontrolling various drives and pressures. The memory is coupled to theCPU. The memory, or computer-readable medium, may be one or more ofreadily available memory such as random access memory (RAM), read onlymemory (ROM), floppy disk, hard disk, or any other form of digitalstorage, local or remote. The support circuits are coupled to the CPUfor supporting the processor in a conventional manner. These circuitsmay include cache, power supplies, clock circuits, input/outputcircuitry, subsystems, and the like.

The factory interface 102 generally houses the substrate transfermechanism 120. The factory interface 102 generally includes a pluralityof bays 128 on the side opposite the transfer chamber 104. The bays 128are configured to accept a substrate storage cassette 130. Opposite thebays 128 are ports 136 that coupled the factory interface 102 to theload lock chambers 106. The substrate transfer mechanism 120 istypically coupled to a guide 132 that is movably disposed on a rail 134.An actuator (not shown) is coupled between the factory interface 102 andthe guide 132 so that the guide 132 and substrate transfer mechanism 120may be controllably positioned along the rail 134. Thus, the substratetransfer mechanism 120 may be positioned proximate any of the cassettes130 or the load locks 106 to facilitate transfer of the substrate 124therebetween. An example of one factory interface that may be adapted tobenefit from the invention is described in U.S. patent application Ser.No. 09/161,970, filed Sep. 28, 1998 by Kroeker, which is herebyincorporated by reference in its entirety.

FIG. 2 depicts one embodiment of the substrate transfer mechanism 120.The substrate transfer mechanism 120 generally includes a body 202, ashaft 204, a robot arm 206 and an end effector 208. The body 202generally houses the robot's motor. The shaft 204 extends from the body202 and is rigidly coupled to the robot arm 206. The shaft 204 maycontrollably rotate, extend and retract into the body 202 as directed bythe controller. The arm 206 includes a first strut 210 and a secondstrut 212 that are pivotally coupled at an elbow 214. The first strut210 is rigidly connected to the shaft 204 opposite the elbow 214. Awrist 216 couples the second strut 212 to the end effector 208. Thewrist 216 is generally rigid but may optionally pivot or include arotary actuator. An example of a transfer mechanism that may be adaptedto benefit from the invention is described in U.S. patent applicationSer. No. 09/272,658, filed Mar. 18, 1999 by Sundar, which is herebyincorporated by reference in its entirety.

The end effector 208 of the substrate transfer mechanism 120 generallyretains and supports the substrate during transfer between locations.The end effector 208 generally includes a plurality of seats 218disposed thereon. Each seat 218 is typically fabricated from a polymericmaterial to minimize particle generation and substrate scratching whichcould occurs when the substrate is in contact with the seats 218. Eachseat 218 typically includes a base 220 and a lip 222. The base 220 isgenerally parallel to the end effector 208 and supports the bottom ofthe substrate. The lip 222 projects from the base 220 and is typicallyperpendicular thereto. The seats 218 are generally disposed on the endeffector 208 such that the lips 222 bound the perimeter of the substratewhen seated on the seats 218. In one embodiment, the lip 222 is curvedto substantially equal the radius of the substrate. As such, the lips222 prevent the substrate 124 from sliding off the bases 220 of theseats 218 as the end effector 208 is moved by the substrate transfermechanism 120.

FIG. 3 depicts a plan view of the substrate transfer mechanism 120illustrating the motion of the end effector 208 about the body 202. Themotion illustrated in FIG. 3 may be referred to as “polar” motion. In arotational mode, the end effector 208 may be rotated about the body 202of the substrate transfer mechanism 120 by rotating the shaft 204 whilethe elbow 214 maintains an angle 302 constant between the first strut210 and the second strut 212. In the rotational mode, the end effector208 is maintained at a constant radius from the centerline of the shaft204. In a extension or retraction mode, the end effector 208 may beextended and retracted by rotating the shaft 204 while engaging alinkage (not shown) in the elbow 214 to increase or decrease the angle302 between the first strut 210 and the second strut 212. For example,when the shaft 204 is rotated clockwise while the angle 302 isdecreased, the end effector 208 moves towards the body 202 of thesubstrate transfer mechanism 120. In a combined mode, the rotational andextension/retraction modes are combined to produce a hybrid motion.

The end effector 208 generally includes a disk 304 and one or moreorientation sensors 308 disposed thereon. The disk 304 is generallyrotatably disposed on the end effector 208. The disk 304, which may bemaintained in contact with or be actuated to contact the substratedisposed on the end effector 208, may be rotated so that an indicia 306of the substrates orientation (i.e., a notch, flat or the like) may berotated above the orientation sensor 308. The orientation sensor 308,which is coupled to the controller, provides a signal that is indicativeof the indicia's position proximate the orientation sensor 308, thusestablishing the substrate's orientation on the end effector 208. Thedisk 304 may include an optional vacuum port 334 disposed therein toretain the substrate to the disk 304.

In one embodiment, the end effector 208 generally includes a centerportion 310 having a first tab 312, a second tab 314 and a third tab 316extending therefrom. Each tab 312, 314, 316 has one of the substratesupport seats 218 (individually shown as 318A, 318A and 318B) disposedthereon. Generally, the tabs 312, 314, 316 are orientated in so that thesubstrate 124 is supported by the seats 318A, 318B when disposed on theend effector 208 in a stable position that maintains the substrate 124on the end effector 208 without falling during transport. As such, it iscontemplated that the geometry of the end effector 208 is scaled toaccommodate substrates of different diameters. Generally, one seat,preferably the seat 318A that is disposed on the first tab 312, ismovable towards the center portion 310 to allow the substrate 124 to begripped between the seats 318A, 318B, thereby centering the substrate onthe end effector 208 and disk 304.

The first tab 312 generally couples the center portion 310 to the wrist216 of the substrate transfer mechanism 120. In one embodiment, thefirst tab 312 includes an actuator, such as a pneumatic cylinder,solenoid or the like, coupled thereto. A plunger 322 of the is coupledto the seat 318A that is disposed on the first tab 312. The plunger 322,when urged by the actuator 308, moves the seat 318A inwardly toward thestationary seats 318B coupled to each of the second and third tabs 314,316, thus gripping the substrate 124 therebetween.

The second tab 314 and the third tab 316 are disposed on the side of thecenter portion 310 opposite the first tab 312. Typically, the second tab314 and the third tab 316 are disposed as mirror images to either sideof an imaginary line defined between the first tab 312 and the center ofthe center portion 310.

In one embodiment, a substrate sensor 324 is disposed on the second tab316 for detecting the proximate of an object 332 to the end effector208. The sensor 324 may be an optical sensor. The sensor 324 may be usedalone or in tandem with a reflector or receptor 326 that is disposed onthe third tab 318. When the object 332 disrupts a beam, such as a lightwave, passing between the sensor 324 and the receptor 326, a signal isgenerated by either the sensor 324 or receptor 326 indicating thepresence of the object 332 therebetween. As the sensor 324 and receptor326 are position on the second and third tabs 314, 316 outward of thesubstrate's perimeter when disposed on the end effector 208, the sensor324 and receptor 326 may be utilized when the substrate 124 is disposedon the end effector 208. This configuration is particularly useful indetecting objects 332 such as substrates in the substrate storagecassette 130. Alternatively, other types of sensors (used alone or intandem) that detect the presence of an object may be utilized in placeof the sensor 324 and receptor 326, for example, proximately sensors,limit switches, optical sensors, pressure transducers and the like.

At least one orientation sensor 308 is typically disposed on one of thetabs 312, 314 or 316. The orientation sensor 308 is generally positionedat a radial distance from the center of the center portion 310 equal tothe radius of the substrate for which the end effector 208 is designedto transfer. The sensor 308 is typically a proximately sensor thatdetects the presence of the substrate thereover. Alternatively, theorientation sensor 308 may be a through beam sensor, a reflective sensoror a CCD camera. Such sensors are generally available from a number ofcommercial sources such as Keyence Corporation, of Woodcliff Lake, N.J.The orientation sensor 308 provides a signal indicative of the passingof the indicia 306 thereover as the substrate 124 is rotated. Forexample, the sensor 308 may have an optical detection means thatprovides a signal (which may be configured to be no signal) in responseto the reflectivity of the substrate when disposed proximate thereto.Since the indicia 306 provides a discontinuity in the reflectivity seenby the sensor 308, the indicia 306 passing over the sensor 308 causes achange in signal level. The difference in signals provided by the sensor308 in response to the discontinuity (i.e., the indicia 306) passingover the sensor 308 is indicative of the substrate's orientation. Thesignal information is provided to the controller which logs the event inrelation to the angular position of the disk 304, thus providing areference of the substrate's orientation for use when positioning thesubstrate 124 in process chambers 108 which require a particularorientation during processing.

Alternatively, more than one orientation sensor 308 may be disposed onthe end effector 208. Since the indicia 306 typically is disposed in asingle location, having multiple sensors 308 disposed on the endeffector 208 may reduce the time required for the indicia 306 to rotateover one of the orientation sensors 308. For example, a secondorientation sensor 328 may be disposed on the end effector 208. In oneembodiment, the second orientation sensor 328 is disposed on the firsttab 312. Optionally, additional orientation sensors, such as a thirdorientation sensor 330 disposed on the third tab 316, may be utilized.Any one of the sensors 308, 328 and 330 may be elongated a radialorientation relative to the center of the disk 304 so that the indicia306 may be detected on substrates that are disposed off-center on thedisk 304.

Optionally, the orientation sensor 308 may be disposed remotely to theend effector 208. For example, one or more sensors 308 may be disposedanother component of the substrate transfer mechanism 120, in thesubstrate storage cassette 130, in the factory interface 102, in thetransfer chamber 104, in the load lock chamber 106, in the one or moreprocess chambers 108, in the various ports or other locations within thesystem 100 where the indicia 306 disposed on the substrate 124 may beviewed.

FIGS. 4 and 5 depict the end effector 208 with the disk 304 removed toshow a motor 410. A hub 402 is centrally disposed on the center portion310 of the end effector 208. The disk 304 typically includes a flange502 that at least partially circumscribes the hub 402. A bearing 504 maybe disposed between the flange 502 and hub 402 to enhance the rotationto the disk 304. An annular pocket 414 circumscribes the hub 402 andextends into the center portion 310. A pocket bottom 412 generallyextends between an outer wall 408 and the hub 402 thereby defining thepocket 414.

The motor 410 is disposed in the pocket 414 of the end effector 208. Themotor 410 generally comprises a casing 418 that is disposed proximatethe outer wall 408 and includes a plurality of armatures 416 extendinginwardly therefrom. Each armature 416 includes a core 404 having acircumscribing conductive winding 406. The windings 406 of alternatingarmatures 416 are electrically coupled through the casing 418.

The motor 410 additionally includes a plurality of permanent magnets 506are disposed on an outer surface 508 of the flange 502. The magnets 506may be disposed on an inner race of the motor 410 (not shown) that ispress-fit or adhered to the flange 502 of the disk 304. As the windings406 are energized, the magnets 506 are urged in a rotary motion thatcauses the disk 304 to rotate. The magnets 506 circumscribe the flange502 and are generally arranged in alternating polarity. As thecontroller (or other power source) energizes the winding 406 with analternating current, the windings 406 alternately attract and repelmagnets 506 having a given polarity as to cause the disk 304 to rotateon the hub 402 in a conventional fashion. Alternatively, the disk 304may be rotated through other means, for example, a belt, gear assemblyor drive shaft coupled to a motor or solenoid positioned on or remote tothe end effector 206.

Optionally, an encoder 510 may be coupled to the end effector 208proximate the disk 304. The encoder 510 is coupled to the controller 150to provide closed-loop information regarding the angular position of thedisk 304.

FIG. 6 depicts another embodiment of an end effector 600. The endeffector 600 is generally substantially similar to the end effector 208described above except that the end effector 600 includes an actuator602 disposed thereon for elevating the substrate 124 relative to the endeffector 600. In one embodiment, a hub 604 centrally disposed in the endeffector 600 at least partially houses the actuator 602. The actuator602, which may be a solenoid, may be actuated to lift the substrate 124clear of the seats 218 as shown. In the lifted position, the substrate124 may be rotated by the disk 304 without touching the seats 218, thusminimizing particle generation and the chance of scratching of thesubstrate during rotation. Other means for actuating the substratenormally to the end effector 600 include lead screws, pneumaticcylinders, hydraulic cylinders, electromagnetic actuators, cams, fluidjets and the like. A substrate 124′ depicted in phantom is shown in alowered position supported by the seats 218.

FIGS. 1 and 3 may be referred to during the following description of onemode of operation. Generally, the substrate transfer mechanism 120 movesproximate one of the substrate storage cassettes 130. Using thesubstrate sensor 324 and receptor 326, the presence of a substratewithin the storage cassette 130 is confirmed before gripping thesubstrate. The end effector 208 of the transfer mechanism 120 thenextends into the cassette 130 to retrieve the substrate. The substrateis gripped by moving the seat 318A towards the stationary seat 318B. Theend effector 130 is then retracted and the substrate is moved to theload lock 106.

Typically during movement of the substrate between the cassette 130 andload lock 106, the first seat 318A is moved slightly outward to relaxthe grip on the substrate. Once the substrate can rotate across theseats 318A, 318B, the motor assembly 410 is energized to rotate the disk304. As the disk 304 supporting the substrate rotates, the indicia 306passes over the orientation sensor 308, indicating the angularorientation of the substrate. The controller stores the substrate'sorientation information in the controller's memory for use whenpositioning the substrate in those process chambers 108 that requiresubstrate orientation. Alternatively, the orientation of the substrateoccurs while the end effector 208 is stationary. In another mode ofoperation, once the orientation of the substrate is determined, thesubstrate is rotated to place the indicia 306 in a predefinedorientation relative to the end effector 208.

As stated above, the substrate transfer mechanism 120 having thecapability for orientating the substrate is not limited to theillustrative embodiment described above. For example, a robot having anend effector that includes a rotating disk and at least one sensor maybe utilized outside of a vacuum environment or other chamber.

Another example of a substrate transfer mechanism 700 is depicted inFIG. 7. The substrate transfer mechanism 700 generally includes an endeffector 702 coupled to a frog-legged robot 704. The end effector 702 issubstantially similar to the end effector 208 described above. The robot704 includes a pair of concentric drive motors 706, 708 regulated by thecontroller. The robot 704 includes a pair of robot arms 710 eachincluding a first strut 712 rigidly connected to a respective drive 706,708. A second strut 714 of the robot arm 710 is pivotally connected tothe first strut 712 by an elbow pivot 716 and by a wrist pivot 718 to acommon rigid connecting member 722. The connecting member 722 is coupledto the end effector 702. The structure of the struts 712, 714 and pivots716, 718 form a “frog-leg” linkage that is actuated in a conventionalmanner to rotate, extend and retract the end effector 702. The substratetransfer mechanism 700 may be utilized in any number of locationsrequiring transfer and/or orientation of the substrate. Additionally,the substrate transfer mechanism 700 may include more than one endeffector 702, for example, a second end effector coupled to the robot704 or to a second robot mounted concentrically to the robot 704 (secondend effector and second robot not shown). One location where thesubstrate transfer mechanism 700 may be utilized in dual end effectorconfiguration is in place of one or both of the transfer robots 112A,112B disposed in the transfer chamber 104 of FIG. 1. An example of arobot that may be modified to benefit from the invention is described inthe previously incorporated U.S. patent application Ser. No. 09/272,658.

Although the teachings of the present invention that have been shown anddescribed in detail herein, those skilled in the art can readily deviseother varied embodiments that still incorporate the teachings and do notdepart from the scope and spirit of the invention.

1. Apparatus for transferring a substrate comprising: a chamber; a robot disposed in the chamber and having at least one end effector adapted to support the substrate; at least one sensor disposed on the end effector, the sensor adapted to detect an inidicia of orientation of the substrate; a disk coupled to the end effector; a motor coupled between the disk and the end effector, wherein the motor rotates the substrate disposed on the disk relative to the end effector; and an actuator coupled to the disk, the actuator for elevating the disk relative to the end effector.
 2. The apparatus of claim 1, wherein the chamber is a vacuum chamber.
 3. The apparatus of claim 1 further comprising one or more substrate storage cassettes coupled to the chamber. 